Lung Cancer

Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary lung cancers, are carcinomas that derive from epithelial cells. The most common symptoms are shortness of breath, coughing (including coughing up blood), and weight loss.

The main types of lung cancer are small-cell lung cancer (SCLC), also called oat cell cancer, and non-small-cell lung cancer (NSCLC). The most common cause of lung cancer is long-term exposure to tobacco smoke. Nonsmokers account for 15% of lung cancer cases, and these cases are often attributed to a combination of genetic factors, radon gas, asbestos, and air pollution including secondhand smoke.




Symptoms that may suggest lung cancer include:[15]

• Dyspnea (shortness of breath)
• Hemoptysis (coughing up blood)
• Chronic coughing or change in regular coughing pattern
• Wheezing
• Chest pain or pain in the abdomen
• Cachexia (weight loss), fatigue, and loss of appetite
• Dysphonia (hoarse voice)
• Clubbing of the fingernails (uncommon)
• Dysphagia (difficulty swallowing).

If the cancer grows in the airway, it may obstruct airflow, causing breathing difficulties. The obstruction can lead to accumulation of secretions behind the blockage, and predispose to pneumonia. Many lung cancers have a rich blood supply. The surface of the cancer may be fragile, leading to bleeding from the cancer into the airway. This blood may subsequently be coughed up.

The lung is a common place for metastasis of tumors from other parts of the body. Secondary cancers are classified by the site of origin; e.g., breast cancer that has spread to the lung is called breast cancer. Metastases often have a characteristic round appearance on chest radiograph. Solitary round lung nodules are not infrequently of an uncertain etiology and may prompt a lung biopsy.

The long-term use of supplemental multivitamins (such as vitamin C, vitamin E, and folate) does not reduce the risk of lung cancer. Indeed long-term intake of high doses of vitamin E supplements may even increase the risk of lung cancer. However, eating at least five servings of fruits and vegetables per day and following a diet that conforms to the American Cancer Society's guidelines may help lower risk.

article source: wikipedia